The filter apparatus mentioned above is utilized in various industry fields. For example, it is utilized in cooling water in a thermal power station and a nuclear power station, water used for hydraulic power generation, water and sewerage corresponding to daily life water, agricultural water, cooling installation such as a heating furnace, a rolling machine, a compressor, a chemical reactor, a distilling apparatus and the like in iron manufacturing, ceramic industry and chemical industry, a producing apparatus for producing fresh water from sea water, sprinkler water spraying equipment and the like. In other words, it is necessary to carry out a water treatment of water, river water, lake water, the sea water and the like, and it is necessary to remove the foreign material by the filter apparatus for the purpose of protecting a water treating machine or the like, in an initial stage of the water treatment. As a target foreign material, there are various materials such as earth and sand, sludge, a wood piece, a metal piece, a plastic piece, a fish, a shell fish, an algae and the like.
A basic structure of the filter apparatus is provided with a cylindrical main body container, and a filter element (a filter) set in an inner portion thereof, introduces a liquid to be filtered such as the water, the sea water or the like into the main body container, and removes the foreign material contained in the liquid by the filter element.
The liquid from which the foreign material is removed is discharged from an outflow pipe, and is utilized as cooling water, recirculated water or the like for the various purposes as mentioned above. The removed foreign material is discharged from a drain pipe at an appropriate timing together with the inflow liquid, and is thereafter disposed. One of the filter apparatus having the purpose mentioned above includes a swirling vortex filter apparatus (a vortex strainer). As the filter apparatus, there have been known structures disclosed in the following Patent Documents 1 and 2. Each of the filter apparatuses has an inflow pipe, an outflow pipe, and a filter tank (a main body container) having a discharge pipe discharging a foreign material, and is provided with a cylindrical or an inverted circular truncated cone shaped filter element fixed within the filter tank. The liquid inflowing from the inflow pipe constructs a swirling flow within the filter tank. It is possible to separate and concentrate the foreign material contained in the liquid by a centrifugal force, by generating the swirling flow, and to discharge it together with the liquid via a drain pipe. Further, Each of the filter apparatuses has a function of self cleaning the foreign material attached to a front face of the filter element by a peeling effect, by generating the swirling flow.
Patent Document 1: Japanese Unexamined Patent Publication No. 2000-291124
Patent Document 2: Japanese Unexamined Patent Publication No. 2003-190713